Hand torch



M. N. STATES May 8, 1934.

HAND TORCH Filed Jan. 15 1952 if nl 56 Patented May 8, 1934 HAND TQRCH Marshall N. States, Evanston, Ill., assignor to Central Scientific Company, a corporation of Illinois Application January 15, 1932, Serial No. 586,854

2 Claims.

This invention relates to a hand torch and has for its principal object to improve the character and stability of the flame.

Further and other objects and advantages will become apparent as the disclosure proceeds and the description is read in conjunction with the accompanying drawing, in which Fig. 1 is a plan view of the improved torch, a portion of the hand grip being broken away;

Fig. 2 is a sectional View through the delivery end of a preferred form of the invention;

Fig. 3 is identical with Fig. 2 with the exception that the fuel nozzle and air nozzle terminate at the same point;

Fig. 4 illustrates a further modification of the torch shown in Fig. 2, in this modification the shield being in the form of an enlarged cylindriv cal barrel; and

' Fig. 5 is a perspective View of the shield shown in Figs. 2 and 3.

Although only three embodiments of the invention have been illustrated in the drawing and are herein specifically described, it will be understood that the invention may be embodied in various other forms within the scope of the appended claims.

Hand torches, or blow pipes as they are sometimes called, are commonly used in scientific laboratories as a source of intense heat. They are particularly useful in sealing glass and in repairing large pieces that are not easily handled.

Hand torches of this general type range in their adjustment from a needle point flame to a brush flame. The needle point flame is advantageously used when it is desired to concentrate the heat on a relatively small area, while the brush name is best employed where large surfaces are to be heated.

Certain phenomena that are not easily explained are observe-d in the burning of the needle point and brush flames. rI'he first of these is the tendency for a yellow secondary flame to form adjacent the fuel nozzle during the needle point adjustment which not only detracts from the efflciency of the name, but also forms carbon deposits that are objectionable.

The second phenomenon is observed when a brush flame is used and is characterized by a zone of non-combustion between the llame and the delivery nozzle. This renders the flame very unstable, and quick movement of the torch through the air will cause it to go out.

Various theories might be expounded in explanation of these phenomena, but it is sufficient here to observe that they exist and to disclose means for overcoming their disadvantages.

Referring now to the drawing, and particularly to Fig. 1, the torch includes a handle portion or hand grip 10, (the major portion, however, being broken away) comprising parallel fuel and air tubes 11 and 12, respectively, rigidly joined togetner at 13 and 14. The ends of the tubes adja- 6 cent the cross member 14; are ribbed as at 15 for connection with suitable fuel and air hoses, not shown.

rI'he fuel tube 11 is extended at 16 and enters the side of a fuel nozzle 17 at 18, to which it is 65 secured by suitable means, for example, by soldering. The air tube 12 is similarly extended at 19 and bowed at 20, thus bringing the delivery end in position to pass through the end of the fuel nozzle at 21 and be supported concentrically therein. 70 The joint 21 is also preferably soldered.

Suitable stop cocks 22 and 23 are interposed between the fuel pipes 11 and 16, and air pipes 12 and 19, respectively. Their position adjacent the handle portion makes for convenience in adjusting the torch flame while in actual use.

The fuel nozzle 17 comprises a rod 24 drilled at 25 toprovide a fuel passage 26. This passage is in direct communicaiton with a source of fuel through the tube extension 16.

The air tube 19 which passes through the axial bore 27 in the rod 24 terminates in the embodiments of the invention shown in Figs. 2 and 4 at a point 28 somewhat beyond the end 29 of the fuel nozzle. Preferably, the tip 28 of the air tube or nozzle 19 is spun over to provide a restricted opening 30, although in some instances better results are obtained when the air orice is unrestricted, for example when a relatively large flow of air at low velocity is desired.

An adjustable shield, generally designated 31 (Figs. 2, 3 and 5) is sleeved on the fuel nozzle 17 and is provided with an outwardly flared mouth 32. A 30 cone surface for the mouth of the shield has been found to be Very satisfactory. The sleeve is preferably provided with an integral thumb nut 36 for convenience in adjustment.

The torch shown in the drawing can be used with most fuel gases within a range of 500 to 1200 B. t. u.s and the blast can be supplied by either compressed air, oxygen, or any other oxidizing gas.

As fuel and air are admitted into the tube extensions 16 and 19, respectively, in regulated quantities by suitable manipulation of the stop cocks 22 and 23, the fuel is carried through the annular space 26 surrounding the air nozzle into the enclosed area defined by the walls of the adjustable shield 31. All or part of this fuel will '110 be sucked into the air stream emerging through the aperture 30 and when ignited will burn With a flame having characteristics depending upon the adjustments of fuel and air and the position of the adjustable shield 31.

It has been found by experiment that by cutting back the fuel nozzle to the point 29 (as compared with the structure shown in Fig. 3) and by equipping the fuel nozzle with a shield having an outwardly flared mouth, the character and stability of the torch flame are greatly improved. It is not precisely understood Why this is so, but the most plausible theory seems to be that the fuel, by being permitted to expand into a protected space of substantially greater cross sectional area than that of the fuel nozzle 17, mixes with air drawn into the shield by the reduced pressure adjacent the air stream and forms a secondary llame or zone of combustion that serves as a pilot light or stabilizer for the main llame. In other words, the outwardly ared mouth of the cone provides a mixing chamber of sufficient size to produce a zone of secondary combustion that will prevent the flame from being blown out when the torch is moved quickly through space.

The advantageous results secured by the torch nozzle assembly shown in Fig. 2 are also secured, but to a lesser extent, in the form of the invention shown in Fig. 3 which is identical with Fig. 2 with the exception that the fuel nozzle 33 extends up to the tip 28 of the air nozzle. The thickness of the tube 33 occupies some of the space which would otherwise be available for secondary combustion and is, therefore, not as desirable as the construction shown in Fig. 2.

In Fig. 4, there is shown a second modification of the invention which diifers from the embodiment of Fig. 2 only in the form of the adjustable shield, here designated 34. In this instance, the shield comprises a sleeve portion 35 which telescopes with the fuel nozzle 17. The sleeve 35 is enlarged at its forward end to provide an open cylindrical barrel 37.

This form of the devices operates very satisfactorily and produces a stable flame. According to the theory advanced above, this would naturally follow because the barrel 37 provides a protected area well suited for secondary combustion.

It will be seen that in each of the three embodiments shown in Figs. 2, 3 and 4, an enlarged protected space is provided beyond the fuel nozzle and it is this feature which is believed to effect the desired results.

The use of the term air throughout the speciiication and claims is intended to include any kind of oxidizing gas as for example oxygen itself.

What I claim, therefore, is:

l. In a hand torch of the type including an air nozzle concentrically mounted within a fuel nozzle, the combination therewith of an imper- 95 forate shield telescopically mounted over the fuel nozzle and adjustable lengthwise along the nozzle, said shield having an outwardly flared mouth projecting beyond the tip of the air nozzle and Y providing a protected space of substantially 109 greater cross sectional area than the fuel nozzle, whereby combustion is restricted to a single hot flame of improved stability wherein substantially complete combustion takes place.

2. In a hand torch, a substantially unobstructed 195 fuel nozzle, an air nozzle concentrically mounted within the fuel nozzle, and a shield telescopically mounted over the fuel nozzle and adjustable lengthwise along the nozzle, said shield projecting beyond the tip of the air nozzle and provid- 110 ing a protected space of substantially greater cross sectional area than the fuel nozzle, whereby combustion is restricted to a single hot flame of improved stability wherein substantially complete combustion takes place.

MARSHALL N. STATES. 

